Airfoils for gas turbine engines

Abstract

An airfoil for a gas turbine engine defining a radial direction and an axial direction, the airfoil including: a flared portion extending from a suction surface of the airfoil at an outer edge of the airfoil along the radial direction; and a plenum disposed at the outer edge of the airfoil, the plenum having a suction-side sidewall and a pressure-side sidewall, wherein the suction-side sidewall has a first sidewall portion adjacent to a second sidewall portion disposed outside of the first sidewall portion along the radial direction, wherein the first sidewall portion defines a first angle, wherein the second sidewall portion defines a second angle, and wherein the first angle is greater than the second angle.

What is claimed is: 
     
       1. An airfoil for a gas turbine engine defining a radial direction, the airfoil comprising:
 a flared portion extending from a suction surface of the airfoil at an outer edge of the airfoil along the radial direction, the flared portion spaced apart from a trailing edge of the airfoil and a leading edge of the airfoil; and 
 a plenum disposed at an outer edge of the airfoil, the plenum having a suction-side sidewall and a pressure-side sidewall; 
 wherein the suction-side sidewall has a first sidewall portion adjacent to a second sidewall portion disposed radially outside of the first sidewall portion; 
 wherein the first sidewall portion defines a first angle with the radial direction as measured by an average angular offset between the radial direction and the first sidewall portion; and 
 wherein the second sidewall portion defines a second angle with the radial direction, less than the first angle, as measured by an average angular offset between the radial direction and the second sidewall portion. 
 
     
     
       2. The airfoil of  claim 1 , wherein the outer edge of the airfoil is configured to be spaced apart from a shroud of the gas turbine engine by a clearance distance, CLR, wherein the second sidewall portion has a radial height, h, and wherein h/CLR is greater than 2. 
     
     
       3. The airfoil of  claim 1 , wherein a suction surface of the flared portion is angularly offset from the radial direction of the airfoil by a third angle as measured by an average angular offset between the radial direction and the suction surface of the flared portion, and wherein the third angle is approximately equal to the first angle. 
     
     
       4. The airfoil of  claim 1 , wherein the airfoil further comprises a cooling cavity disposed within a body of the airfoil, and wherein the cooling cavity is in fluid communication with the outer edge of the airfoil through one or more cooling holes extending between the cooling cavity and the outer edge of the airfoil. 
     
     
       5. The airfoil of  claim 4 , wherein at least one of the one or more cooling holes comprises a first size, as measured at a first radial location along the one or more cooling holes, and a second size, as measured at a second radial location along the one or more cooling holes, the second radial location being radially outside the first radial location, and wherein the second size is greater than the first size. 
     
     
       6. The airfoil of  claim 5 , wherein the second radial location corresponds with the outer edge of the airfoil. 
     
     
       7. The airfoil of  claim 1 , wherein the flared portion extends less than 80% of a chord length, c, of the airfoil, as measured at the outer edge of the airfoil. 
     
     
       8. The airfoil of  claim 1 , wherein the flared portion has a tapered profile. 
     
     
       9. The airfoil of  claim 1 , wherein the outer edge of the airfoil defines a recess disposed between and spaced apart from the plenum and a suction surface of the flared portion, as measured at the outer edge of the airfoil. 
     
     
       10. A gas turbine engine defining a radial direction, the gas turbine engine comprising:
 a shroud; and 
 a turbine positioned at least partially inward of the shroud along the radial direction, the turbine having a plurality of airfoils, with at least one airfoil in the plurality of airfoils comprising:
 a flared portion extending from a suction surface of the airfoil at an outer edge of the airfoil; and 
 a plenum disposed at the outer edge of the airfoil, the plenum having a suction-side sidewall and a pressure-side sidewall; 
 
 wherein the flared portion extends no greater than 80% of a chord length of the airfoil, as measured at an outer edge of the airfoil, and is spaced apart from a trailing edge and a leading edge of the airfoil; 
 wherein the suction-side sidewall has a first sidewall portion adjacent to a second sidewall portion disposed radially outside of the first sidewall portion; 
 wherein the second sidewall portion is approximately normal to an inner surface of the shroud; and 
 wherein the first sidewall portion is angularly offset from the second sidewall portion. 
 
     
     
       11. The gas turbine engine of  claim 10 , wherein the outer edge of the at least one airfoil is spaced apart from the shroud by a clearance distance, CLR, wherein the second sidewall portion has a radial height, h, and wherein h/CLR is greater than 2. 
     
     
       12. The gas turbine engine of  claim 10 , wherein the first sidewall portion and the second sidewall portion lie along best fit lines that intersect at a junction having a junction angle, β, of at least 5°. 
     
     
       13. The gas turbine engine of  claim 10 , wherein the at least one airfoil further comprises a cooling cavity disposed within a body of the at least one airfoil, and wherein the cooling cavity is in fluid communication with the outer edge of the at least one airfoil through one or more cooling holes extending between the cooling cavity and the outer edge of the at least one airfoil. 
     
     
       14. The gas turbine engine of  claim 10 , wherein each airfoil in the plurality of airfoils comprises the flared portion and the plenum. 
     
     
       15. An airfoil for a gas turbine engine defining a radial direction, the airfoil comprising:
 a body having an outer edge and a plenum disposed at the outer edge, the plenum having a suction-side sidewall and a pressure-side sidewall; and 
 a flared portion extending radially from a suction surface of the airfoil along less than 20% of a radial length of the airfoil, as measured from an outer edge of the airfoil, and also extending less than 80% of a chord length of the airfoil, as measured at the outer edge of the airfoil; 
 wherein the suction-side sidewall has a first sidewall portion adjacent to a second sidewall portion disposed radially outside of the first sidewall portion; 
 wherein the second sidewall portion is approximately parallel with the radial direction; and 
 wherein the first sidewall portion is angularly offset from the radial direction. 
 
     
     
       16. The airfoil of  claim 15 , wherein a suction surface of the airfoil is angularly offset from the radial direction of the airfoil by an angle, α, as measured by an average angular offset between the radial direction and the suction surface of the airfoil, and wherein the first sidewall portion is angularly offset by an angle of approximately α, as measured by an average angular offset between the radial direction and the first sidewall portion. 
     
     
       17. The airfoil of  claim 15 , wherein a surface of the flared portion is disposed at an angle, a, as measured relative to the radial direction, wherein a pressure surface of the airfoil is disposed at an angle, γ, as measured relative to the radial direction at an approximately same relative height in the radial direction as α, and wherein γ is less than α.